Tear gas is banned for use in warfare by the Geneva Convention. It's allowed, however, to be used by police as "domestic riot control," as seen in protests in Turkey, Bahrain, and now Ferguson, Missouri. Here's what you need to know about tear gas: What it is, and what it does to the human body.

Tear gas is a relatively modern invention—a non-lethal repellant developed from the killer chemical weapons of World War I. But each canister relies on the fascinating chemistry of some ancient compounds and reactions. Wired gives us a look inside, without all the coughing and choking.

If you're rioting/looting/celebrating the victory of your local ballgame squad, and you see a cop with one of these—run in the opposite direction. The Crowd Buster is well-named, firing five gallons of pepper spray up to 150 feet.

Seemingly lifted straight from some B-movie horror flick, a group of mourners in Uganda were sprayed by the police with water cannons filled with pink dye. The police said they were only "preventing the worst from happening."

Houston police officer Mike Hamby is facing some serious What the hell, man questioning from his colleagues after attacking a rival team during a rodeo BBQ competition. Stop and process that sentence. Nobody knows why Hamby loosed the attack, either.

The tear gas grenades being used to quell protestors in Egypt are actually made right here in the USA. They're intended to cause "tearing of the eyes" and "irritation of respiratory tract and mucous membranes". What's inside the tear gas?